Heating of fluids



June 22, 1937. M. w. BARNES 2,084,307

HEATING OF FLUIDS Filed Sept. 22, 1934 INVENTOR MARION w ARNES ATTOR EY Patented June 22, 1937 UNITED STATES PATENT OFFIQE HEATING OF FLUIDS Application September 22, 1934, Serial No. 745,032

Claims.

7 This invention is more particularly directed to the heating of hydrocarbon oils to the high temperatures required for their pyrolytic conversion.

It embodies improvements to the form of heater 5 now generally known as the double-end-fired type of furnace, which improvements make the furnace particularly adaptable to the simultanee ous treatment of two separate streams of different hydrocarbon oils whereby each oil is subjected 10 to independently controlled heating conditions regulated to suit its particular requirements and whereby each oil is subjected to substantially progressively increasing rates of heating during its flow through the heating coil.

One specific embodiment of the improved furnace structure provided by the present invention comprises two separate combustion and heating zones, means for independently supplying combustible materials in regulated amounts to each combustionzone,means for independentlycontrolling the characteristics of the flame in each combustion zone,aconvection heating zone located between said combustion and heating zones, means for passing hot combustion gases from both combustion and heating zones through said convection heating zone, a fiuid conduit located adjacent the roof of each combustion zone, a fluid conduit located adjacent the floor of each combustion zone, a fluid conduit located within said convection heating zone, means for passing a stream of hydrocarbon oil first through the fluid conduit adjacent the roof of one combustion zone, then through the fluid conduit adjacent the floor of the same combustion zone and means for simultaneously passing a stream of different bydrocarbon oil first through the fluid conduit in said convection heating zone, then through the fluid conduit adjacent the roof of the other combustion zone and finally through the fluid conduit adjacent the floor of the last mentioned combustion zone.

The process of the present invention comprises, in its specific embodiment, simultaneously heating two separatestreams of different hydrocarbon oils each under independently controlled heating conditions in the same furnace structure, subjecting each stream to substantially progressively increasing rates of heating during its entire heat treatment and subjecting each oil to independently controlled conversion conditions.

The accompanying diagrammatic drawing is a cross-sectional elevation of one specific form of furnace structure embodying the features of the present invention. The following description of 1 the drawing includes a description of :the operation of the furnace and will serve to more clearly illustrate the methods of heating provided by the process of the invention.

Referring to the drawing, the main structure comprises end walls I and 2, a roof 3, a floor i and side walls which are not indicated in the particular view of the furnace here illustrated. The interior of the furnace is divided by means of bridge walls 5 and 6 into two separate combustion and heating zones 1 and 8 and a centrally located convection heating zone 9.

One or, preferably, a plurality of firing tunnels, designated in the drawing as It and Ill, communicate through the respective end walls l and 2 with the respective combustion and heating zones l and 8. Combustible fuel of any desired form together with any air or steam required for atomization, is supplied by means of burners H and II through respective firing compartments I2 and I2 of the respective firing tunnels l0 and it to the respective combustion and heating zones '1 and 8. A regulated portion or all of the air required for combustion may be supplied to firingcompartments l2 and I2, respectively, by means of suitable regulating shutters or dampers furnace l3 and I3 and is thereby transmitted with the fuel to the respective combustion and heating zones. Additional air for combustion and/or any desired quantity of excess air may be supplied direct to combustion and heating zones l and 8 K by means of the respective air ducts H3, H4, M and H4? controlled by dampers I5, H5, H5 and H5 respectively, said air ducts being located both above and beneath'firing compartments l2 and I2. a

By independently controlling the quantity of fuel supplied to the two combustion and heating zones the temperatures of each may be independently controlled and further control over the heating conditions'in each zone is obtained by independently regulating the relative proportions of fuel and air supplied to each combustion zone. The characteristics of thefiames in each combustion zone are independently controlled by regulating the amount of excess air supplied to each. combustion zone and by the provisions for. controlling the method of introducing the air to each combustion zone. By varying the relative quantities of air supplied to the combustion zones above and beneath the firing compartments more or less heat may be concentrated, as desired, alongthe roof or along the floor of each combustion zone. The length and luminosity of the flame in each combustion zone'may be controlled,

withoutvarying the fuel fair ratio,by regulating the proportion of the total air supplied to each combustion zone through firing compartments l2 and i2 respectively as compared with that supplied through the upper and lower air ducts.

A fluid conduit l1 comprising, in the case illustrated, a single horizontal row of horizontally.

disposed tubes I6; extending between the side Walls of the furnace parallel to end wall I, is located adjacent the roof of combustion and heating zone 1 and a similar fluid conduit 18 is located adjacent the floor of the same combustion zone. Another similar fluid conduit I9 is lo-' cated adjacent the roof of combustion and heating zone 8, which also contains another similar fluid conduit 20 located adjacent its floor. Although each of the tube banks or fluid conduits l1, l8, l9 and 25 comprise, in the case here illustrated, a single horizontal row of. tubes it is, of course, within the scope of the invention to employ more than a single row of tubes in any or all of the banks and it is also within the scope of the invention to employ tubes of either the 'same or different size in the various banks, al-

though the tubes are all indicated in the drawing by the reference number l6. Another fluid conduit 2! comprising, in the case here iilustrated, a plurality of super-imposed horizontally and from the hot refractory walls of the furnace to the tubes of banks I1, l8, l9 and 20 predominantly by radiation. The hot combustion gases from combustion zones 1 and 8 pass over the respective bridge walls 5 and 6 and commingle above convection heating zone 9, through which the commingled combustion gases pass, over the tubes of bank 2i, transmitting convection heat thereto, and enter flue 22 from which they pass to a suitable stack not shown.

r In the case here illustrated adjacent tubes in in each "of the banks l1, I8, 19, 20 and 2| are connected at their ends in series by means of suitable return bends located outside the heating zone. The return bends are not illustrated in the drawing but ,the connections between the tubes on the nearside of the furnace are indicated by full single lines while those on the far 7 side are indicated by dotted lines; The solid and dotted lines connecting the various tube banks indicate outside cross-over connections on the near and far side of the furnace, respectively.

'The arrows on these lines indicate the general direction of flow of the oil and the sequence of flow through the various tube banks;

7 In accordance with, the features of the present invention one stream of hydrocarbon oil, comprising, for example, reflux condensate from within the cracking system or gas oil or other dis- .tillate suitable for conversion is supplied to the end tube of bank I! adjacent wall I of the furnace flowing in series through adjacent tubes in this bank to its opposite end, in a general 7 direction concurrent to the direction of firing in combustion and heating zone 1, and is then directed to the end tube of bank l8 adjacent wall I of the furnace, flowing in series through adjacent tubes in this bank in a general direction concurrent to the direction of firing, to be discharged from the end'tube of bank l8 adjacent bridge wall 5 to subsequent portionsof the cracking system not pertinentto the present invenof the combustion gases passing through zone 9 a of the furnace, to the end tube of the uppermost row of this bank, 'wherefrom it passes to the end tube of bank l9 adjacent bank ll, flowing in series through adjacent tubes of this bank, in a general direction countercurrent to the-direction of firing in combustion and heating zone 8, to the end tube of this bank adjacent wall 2, from which it passes to the end tube of bank 20 adjacent wa1l'2, flowing, in, series through adjacent tubes of this bank, ina general direction concurrent to the direction of firing, to be discharged from the end tube of bank 20 adjacent bridge wall 6 to subsequentportions of the cracking system not pertinent to the present invention.

' It will be understood that various modificae tions of thespeciflc flow above describedmay be employed without departing from the spirit and scope of the present invention. For exam ple, the direction of flow through any of the various banks may be reversed, when desired,

and, when desired, all or a portion of the tubes of in series. a

It is also specifically withinthe scope of the present invention to omit the tubes of bank l9 which'are directly above convection heating zone 9 of the furnace. This section of bank I9 is indicated in the drawing at l9.

In such cases in any bank may be connected in parallel instead line 23' instead of line 23 connects tube bank 2| with the remaining portion of bank l9 When this method of flow is employed the temperature of the combustion gases entering convection heating zone Q-isordinarily somewhat higher 1 than when bank I9 is employed, due to the absence of the cooling effect 'of the tubes of bankl9', and consequentlya somewhat higher rate of heating may be obtained in tube bank 2|,

particularly in the upper two or three rows of this bank.

I claim as my invention: a l. A furnace for the heating of fluids "which comprises, in combination, two separateq combustion and heating zones, means for independently supplying combustible fuel in regulated amounts to each combustion and heating zone,

means for independentlycontrollingthe characteristics of the flame and the heating'conditions in each combustion and heatingtzone, a

convection heating zone located between said conduit located within the convection-heating zone, means for passing hydrocarbon oil i .a

continuous stream through the .fluid conduit adjacent the roof of one combustion and heating 1 zone and then through the fluid conduit adjacent the floor of the same zone; means for .r'simul .taneously passing a diilerent hydrocarbon :oil.

in a continuous stream through the fluid conduit in the convection heating zone, then throughthe. fluid conduit adjacent the meter the other. om-

bustion and heating zone and then through the fluid conduit adjacent the floor of the last mentioned combustion and heating zone.

2. A furnace for the heating of fluids which comprises, in combination, two-separate combustion and heating zones, means for independently supplying combustible fuel in regulated amounts to each combustion and heating zone, means for independently controlling the characteristics of the flame and the heating conditions in each combustion and heating zone, a convection heating zone located between said separate combustion and heating zones, means for passing combustion gases from each combustion and heating zone through said convection heating zone, a fluid conduit located adjacent the roof of each combustion and heating zone, a fluid conduit located adjacent the floor of each combustion and heating zone, a fluid conduit located within the convection heating zone, means for passing hydrocarbon oil in a continuous stream through the fluid conduits adjacent the roof and floor of one combustion zone in series and in a general direction concurrent to the direction of firing in said zone and means for simultaneously passing a. different hydrocarbon oil in a continuous stream through the fluid conduit in the convection heating zone and through the fluid conduits adjacent the roof and floor of the other combustion and heating zone in series.

3. In the heating of hydrocarbon oils to conversion temperatures in furnaces of the character having a pair of independently fired com- 7 bustion zones and a convection zone supplied with combustion gases from both said combustion zones, the method which comprises passing a stream of oil first adjacent the roof and then adjacent the floor of one of said combustion zones, and simultaneously passing a second stream of oil first through the convection zone and then adjacent the roof and finally adjacent the floor of the other of said combustion zones,

andsubjecting both said streams to progressively I increasing rates of heating during their flow through the furnace.

4. In the heating ofhydrocarbon oils to conversion temperatures in furnaces of the character having a pair of independently fired combustion zones and a convection zone supplied with combustion gases from both said combustion zones, the method which comprises passing a hydrocarbon oil in a continuous uninterrupted stream through one of said combustion zones adjacent the roof and adjacent the floor thereof, simultaneously passing a second hydrocarbon oil in a continuous uninterrupted stream through the convection zone and through the other of said combustion zones adjacent the roof and adjacent the floor thereof, and subjecting both said streams to progressively increasing rates of heating during their flow through the furnace, the streams being most strongly heated while adjacent the floor of each combustion zone.

5. In the heating of hydrocarbon oils to conversion temperatures in furnaces of the character having a pair of independently fired combustion zones and a convection zone supplied with combustion gases from both said combustion zones, the method which comprises passing a hydrocarbon oil in a continuous uninterrupted stream through one of said combustion zones adjacent the roof and adjacent the floor thereof, simultaneously passing a heavier hydrocarbon oil in a continuous uninterrupted stream through the convection zone and through the other of said combustion zones adjacent the roof and adjacent the floor thereof, and subjecting both said streams to progressively increasing rates of heating during their flow through the furnace, the streams being most strongly heated while adjacent the floor of each combustion zone.

MARION W. BARNES. 

